The present invention concerns a method according to the pre-characterizing clause of claim 1, an associated switching center according to the pre-characterizing clause of claim 7, an associated converter node according to the pre-characterizing clause of claim 8, and an associated service control point according to the pre-characterizing clause of claim 9.
The invention is based on the conventional transmission of service signaling messages in the CCITT signaling system No. 7.
In order to provide specialized ISDN services (ISDN=integrated services digital network), switching centers of a communication network send service signaling messages over the signaling network to each other. These service signaling messages are messages of the SCCP protocol (SCCP=signaling connection control part). To transmit service signaling messages to a destination switching center, an originating switching center enters in the service signaling messages a so-called global title which is the call number of a subscriber of the destination switching center as destination point code. The service signaling messages are then directed to a special signaling node of the communications network. This signaling node then adds to the global title the so-called signaling point code (SPC) which is the address of the destination switching center within the signaling network. Based on this address, the service signaling messages are then directed through the signaling network to the destination switching center.
However, if a subscriber has xe2x80x9cmovedxe2x80x9d with his call number, i.e., can no longer be reached under his unchanged xe2x80x9cpersonalxe2x80x9d call number through the switching center of his former place of residence but rather through a switching center of his new place of residence, and thus into the structure of user channel connections to the switching center of his new place of residence a so-called porting database is inserted in which the call number of the subscriber which is to be ported as well as destination codes to the switching center of his new residence are filed. Also in service signaling messages with respect to the subscriber which must be transmitted in order to render special ISDN services, in the case of such a porting, the global title from the connection exchange area of the switching center of his new residence is no longer entered but rather the global title from the exchange area of the switching center of his new place of residence. In addition, it can be advantageous according to German patent application DE 19805686.9 (internal file no.: 110922) for the aforementioned porting database to also be used. A service signaling message which contains a subscriber code as destination point code is in this way directed to a converting node. In the event of a porting of the subscriber code, the converting node replaces the subscriber code with an assigned, ported subscriber code and in so doing accesses the porting data bank used during connection set-up of a basic channel. To the extent only a single service signaling message which is to be processed in this manner is involved, such a conversion can be managed without problem. However, if several service signaling messages are transmitted within a sequence, it is very time consuming and requires a high level of computing speed for each service signaling message communication to access the porting data base for each service signaling message. In addition, in such an approach, all service signaling messages without exception must be awkwardly directed to the converting node because only in this way can the service signaling message be redirected to the ported destination.
The object of the invention accordingly is to improve the rendering of telecommunication services in which a transmission of service signaling messages for ported call numbers is required.
This object is achieved through a method according to the technical teaching of claim 1 and by a switching center according to the technical teaching of claim 7, a conversion node according to the technical teaching of claim 8, and a service control point according to the technical teaching of claim 9. Additional advantageous embodiments of the invention are contained in the dependent claims and the description.
The invention is based on the idea that as a result of portings of subscriber numbers based on geography or network operator, the routing of service signaling message sequences can be optimized such that a ported subscriber code associated with a former subscriber code is determined only for the first service signaling message, in each case, of a service signaling message sequence through accessing the porting database. The originating switching center which is sending the service signaling message sequence then stores the ported subscriber code and enters it in all service signaling messages within the service signaling message sequence which the originating switching center following the first service signaling message sends to a destination switching center. As a result of the storage of the ported subscriber code in the originating switching center, the time and computing intensive access to the porting database is required only once per service signaling message sequence.
The originating switching center can advantageously query a porting database or a conversion node with a porting database regarding the ported subscriber code.
It is possible in a preferred variant of the invention for the originating switching center to send a first service signaling message of a service signaling sequence to a converting node and for the latter then to determine the ported subscriber code through accessing porting database. The service signaling message sequence is then retransmitted to a destination switching center addressed through the ported subscriber code. The destination switching center then replies to the originating switching station using a response service signaling message from which the originating switching center can determine the ported subscriber code for later use in further service signaling messages of the service signaling message sequence. These further service signaling messages can be transmitted using their now currently applicable ported subscriber code directly to the destination switching center or they can continue to be transmitted via the converting node. In an embodiment according to the invention, the converting node can recognize, however, if a service signaling message is a service signaling message which follows a first service signaling message and already contains a ported, currently valid subscriber code. In this case, the converting node according to the convention omits the time and computing-power intensive access to the porting database.
As a result of the invention, sequences are transferred from service signaling messages correctly and at the same time very efficiently. A change in the service logic is not necessary in order to render the services. The solution according to the invention is also inexpensive and be integrated at low cost into an existing switching system because no changes in the signaling network or in components of the signaling network are necessary. The converting node can be realized particularly inexpensively since for the realization of its function it accesses components which already exist for a different purpose, specifically the porting database and in addition must have essentially only a test function which can distinguish between a first service signaling message and a service signaling message which follows such first service signaling message.
The application of the invention is particularly advantageous in a network environment in which communications networks of various competing network operators exist side by side and in which the requirement for call number portability exists. A further advantageous application case is that of a communications network in which there is a need for call number portability between different subscriber switching stations.